The invention relates to a brown coal dry-distillation method using a coal hot air furnace to supply heat. The brown coal dry-distillation method comprises the following steps of: adding brown coal in a drying furnace to be heated and dried, sending the heated coal into a dry-distillation furnace to be heated and dry-distilled to obtain thermal carbocoal, cooling and quenching the thermal carbocoal in a quenching furnace to obtain a carbocoal product; purifying high-temperature smoke produced by the coal hot air furnace in a purifying room, making dry-distilled coal gas enter into the purifying room, consuming residual oxygen in the high-temperature smoke to produce high-temperature hot air with a low oxygen content as all or partial heating sources of the drying furnace used for coal drying, wherein the dry-distilled heat source in the dry-distillation furnace partially or all comes from the high-temperature smoke produced by burning the dry-distilled coal gas in a burner, and obtaining crude tar and clean dry-distilled normal-temperature coal gas after the following treatments: de-dusting and cooling the dry-distilled coal gas and tar steam, and separating tar and on the like. Compared with the method taking the dry-distilled coal gas as the heat source drying heat source, the high-temperature smoke of the coal hot air furnace is used as the brown coal drying heat source, a lot of dry-distilled coal gas is surplus, such that the saved plenty of dry-distilled coal gas can be for other uses and thus the economic value is high.